A hybrid electric vehicle is a vehicle including a motor in addition to an engine in the related art as a travel driving source, traveling only with the motor being driven or driving the motor to start or assist the engine, or performing regeneration (generation) to charge a battery.
In order to detect a rotation angle and the number of revolutions of the motor, a rotation angle sensor such as a resolver is attached to the motor, and a motor control apparatus (inverter) performs motor control most efficiently based on information on the rotation angle or the number of revolutions from the resolver.
However, because the motor control apparatus (inverter) cannot accurately detect the rotation angle or the number of revolutions of the motor when the resolver or a peripheral circuit thereof fails, it is difficult to normally perform the motor control. Therefore, for a fail safe measure, a method of stopping the motor control and continuing traveling only with the engine is considered, but in this case, because the battery cannot be charged by the motor, a battery capacity is gradually decreased, and as a result, the traveling only with the engine becomes impossible such that the vehicle stops.
Therefore, in PTL 1, when a resolver is determined as abnormal, a motor control continues using a rotation angle detected by a crank angle sensor mounted on a crankshaft of an engine which is rotated while being synchronized with a motor, instead of using a motor rotation angle detected by the resolver. Further, reliability of the motor rotation angle is improved in consideration of a delay of a communication time until rotation angle information is transmitted to a motor control apparatus (inverter) after the rotation angle is detected by the crank angle sensor.